1. Field of the Invention
This invention relates to an indicator lamp comprising a light-emitting element such as a LED (light-emitting diode) and a chip and a converging lens disposed atop and covering the light-emitting element to converge light emitted from the element and, more particularly, to an indicator lamp, which permits a small-size light-emitting element to emit light appropriately in a broad light-emission area and with good efficiency.
2. Prior Art
The light emission zone of a light-emitting element such as a LED is intrinsically a pin-point. Such pin-point light emission lacks directivity and is scattered. It is thus impossible to form a substantially fixed planar light-emission area. Besides, the long distance visual recognition property is deteriorated. Accordingly, a converging lens is usually disposed, which covers the front of the light-emitting element and converges the emitted light.
An indicator lamp using such a lens is well-known in Japanese Utility Model Publication H6-28725. This converging lens has a light-emitting element mounting cavity formed at its bottom, and its peripheral surface which is parabolic in shape from the bottom toward the front, fully reflects light emitted from the light-emitting element such that the reflected light proceeds forwards.
The above light-emitting element lens indeed converges light emitted from the light-emitting element such that the converged light proceeds straight forward as emission light flux with suppression of the scattering of light, thus ensuring excellent long distance visual recognition property. However, since the scattering of light is suppressed, a problem is posed in that the visual field angle as visual range is reduced. Particularly, when the indicator lamp is used as an indicator device, a broad visual field angle is important as well as the long distance visual recognition property.
Besides, the prior art light-emitting element lens has a structure that the lens front is formed with a deep ring-like groove such as to form a convex part at the lens front center. The forming of a lens having such a complicated structure encounters great difficulty. Particularly, in the case of a lens body having a certain height, the ring-like groove may become too deep, and depending on the size and material of the lens, light emitted from the light-emitting element may not always smoothly and efficiently proceed as emission light flux forwards.
To solve the problems as discussed above, it is a primary object of the invention to provide an indicator lamp, which is excellent not only in the short distance visual recognition property but also in the long distance one as well as being further excellent in the visual field angle property.
A second object of the invention is to provide an indicator lamp, which permits, without lens shape complication, light emitted from the light-emitting element to smoothly and efficiently proceed as emission light flux forwards.